Catalyst for exhaust gas purification

Abstract

An object of the present invention is to provide a catalyst for exhaust gas purification, by which exhaust gas can be efficiently purified within a wide temperature range from low to high temperatures. This object can be achieved by using a catalyst for exhaust gas purification, containing a substrate, a lower layer disposed on the substrate, and an upper layer disposed on the lower layer, wherein the lower layer contains: a lower catalytic layer that contains a first material having oxygen storage/release capacity and a first catalytic metal supported on the first material; and a non-catalytic layer that contains a second material having oxygen storage/release capacity but does not contain catalytic metal; in which the lower catalytic layer and the non-catalytic layer are laminated in any order; and an upper catalytic layer that contains a second catalytic metal.

1 . A catalyst for exhaust gas purification, containing a substrate, a lower layer disposed on the substrate, and an upper layer disposed on the lower layer, wherein
 the lower layer contains:   a lower catalytic layer that contains a first material having oxygen storage/release capacity and a first catalytic metal supported on the first material, and   a non-catalytic layer that contains a second material having oxygen storage/release capacity but does not contain a catalytic metal,   wherein the lower catalytic layer and the non-catalytic layer are laminated in any order; and   the upper layer contains an upper catalytic layer that contains a second catalytic metal.   
     
     
         2 . The catalyst for exhaust gas purification according to  claim 1 , wherein the non-catalytic layer is disposed on the lower catalytic layer. 
     
     
         3 . The catalyst for exhaust gas purification according to  claim 1 , wherein the lower catalytic layer is disposed on the non-catalytic layer. 
     
     
         4 . The catalyst for exhaust gas purification according to  claim 1 , wherein the first material having oxygen storage/release capacity and the second material having oxygen storage/release capacity are materials each having a pyrochlore structure. 
     
     
         5 . The catalyst for exhaust gas purification according to  claim 4 , wherein the materials each having a pyrochlore structure are cerium-zirconium composite oxides. 
     
     
         6 . The catalyst for exhaust gas purification according to  claim 1 , wherein the first catalytic metal is rhodium and the second catalytic metal is palladium and/or platinum. 
     
     
         7 . A catalyst for exhaust gas purification, containing:
 a substrate;   a lower catalytic layer disposed on the substrate, wherein the lower catalytic layer contains a first OSC material having a pyrochlore structure and rhodium supported on the first OSC material;   a non-catalytic layer disposed on the lower catalytic layer, wherein the non-catalytic layer contains a second OSC material having a pyrochlore structure but does not contain a catalytic metal: and   an upper catalytic layer disposed on the non-catalytic layer, wherein the upper catalytic layer contains palladium and/or platinum.   
     
     
         8 . A catalyst for exhaust gas purification containing:
 a substrate;   a non-catalytic layer disposed on the substrate, wherein the non-catalytic layer contains a second OSC material having a pyrochlore structure but does not contain a catalytic metal;   a lower catalytic layer disposed on the non-catalytic layer, wherein the lower catalytic layer contains a first OSC material having a pyrochlore structure and rhodium supported on the first OSC material; and   an upper catalytic layer disposed on the lower catalytic layer, wherein the upper catalytic layer contains palladium and/or platinum.